Hydro-mechanical behavior and microstructure evolution of red clay-bentonite backfills

IF 5.3 2区地球科学 Q2 CHEMISTRY, PHYSICAL Applied Clay Science Pub Date : 2023-11-01 DOI:10.1016/j.clay.2023.107111

Kao-fei Zhu , Ke-neng Zhang , Yong He

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引用次数: 2

Abstract

Soil-bentonite (SB) cutoff walls have been extensively used as vertical engineering barriers to control groundwater flow and subsurface contaminant migration. As the pollution containment capability of the SB backfills is intimately related to the hydro-mechanical behavior, consolidation tests and hydraulic conductivity tests were carried out to investigate the effects of bentonite content on the hydro-mechanical behavior of red clay-bentonite backfills, and the microstructure evolution of backfills under vertical loading was evaluated based on mercury intrusion porosimetry (MIP) tests and field emission scanning electron microscope (FESEM) observations. The results of microstructure analysis also evaluated the influence of bentonite on the clay fabric which changed the relationship between hydraulic conductivity and void ratio. The results indicated that the void ratio and hydraulic conductivity decreased linearly with the increase of the effective consolidation stresses, and the compression index decreased with the increase of bentonite content. Meanwhile, the pore size distribution (PSD) curve of the backfill specimen almost turned into unimodal characteristics with only micropores distributed after consolidation. Additionally, the flow paths became more tortuous under compression which decreased the hydraulic conductivity. The montmorillonite aggregates in red clay-bentonite backfill formed into tortuous network structure which bound the clay aggregates together and effectively increased the tortuosity of flow paths.

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红粘土-膨润土充填体水力学行为及微观结构演化

土-膨润土(SB)防渗墙作为控制地下水流动和地下污染物迁移的竖向工程屏障已得到广泛应用。鉴于SB充填体的防污染能力与水力学性能密切相关，通过固结试验和导水试验研究了膨润土含量对红粘土-膨润土充填体水力学性能的影响。通过压汞孔隙度(MIP)试验和场发射扫描电镜(FESEM)观察，对充填体在竖向荷载作用下的微观结构演化进行了评价。微观结构分析的结果还评价了膨润土对粘土织物的影响，它改变了导水率和孔隙率的关系。结果表明:孔隙率和导水率随有效固结应力的增大而线性减小，压缩指数随膨润土含量的增加而减小;同时，固结后充填体的孔隙尺寸分布(PSD)曲线几乎变为单峰特征，只有微孔分布。此外，在压缩下，流道变得更加弯曲，从而降低了水力导率。红粘土-膨润土充填体中蒙脱土团聚体形成扭曲的网状结构，将粘土团聚体捆绑在一起，有效地增加了流道的弯曲度。

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来源期刊

Applied Clay Science 地学-矿物学

CiteScore

10.30

自引率

10.70%

发文量

289

审稿时长

39 days

期刊介绍： Applied Clay Science aims to be an international journal attracting high quality scientific papers on clays and clay minerals, including research papers, reviews, and technical notes. The journal covers typical subjects of Fundamental and Applied Clay Science such as: • Synthesis and purification • Structural, crystallographic and mineralogical properties of clays and clay minerals • Thermal properties of clays and clay minerals • Physico-chemical properties including i) surface and interface properties; ii) thermodynamic properties; iii) mechanical properties • Interaction with water, with polar and apolar molecules • Colloidal properties and rheology • Adsorption, Intercalation, Ionic exchange • Genesis and deposits of clay minerals • Geology and geochemistry of clays • Modification of clays and clay minerals properties by thermal and physical treatments • Modification by chemical treatments with organic and inorganic molecules(organoclays, pillared clays) • Modification by biological microorganisms. etc...